Justification:Naso caeruleacauda is widely distributed in the Coral Triangle Region. It occurs in moderately deep water. It is caught only incidentally in subsistence fisheries and there is no evidence of declines from harvesting. It is found in a number of marine reserves in the Coral Triangle. It is therefore listed as Least Concern.

Naso caeruleocauda was recorded as occasional in terms of relative abundance in the northern Bismarck Sea, Papua New Guinea and in Raja Ampat, Indonesia (Allen 2009, 2003b). It is occasional in the Philippines (R. Abesamis, C. Nanola and B. Stockwell pers. comm. 2010). There was only one school recorded from northwest Madagascar (Allen 2005).

Naso caeruleacauda forms aggregations off seaward slopes, generally at depths greater than 15 m where it feeds on zooplankton. It sometimes swims in mixed schools with Naso hexacanthus.

Reproduction

The sexes are separate among the acanthurids. In Papua New Guinea, it is known to form spawning aggregations in open water above the reef every month of the year during the first and third quarter moon phase. It was reported to spawn early morning and late afternoon with group and pair spawning observed. N. caeruleacauda and N. caesisus are reported to aggregate bimonthly, just prior to the new and full moons. Several hundred species were observed to spawn (Hamilton et al. 2004).

Naso caeruleacauda is occasionally seen in fish markets. In a spawning aggregation site in Papua New Guinea, fishers interviewed state that catch rates have not changed in the years that they have targeted it. It was first exploited in 1999 (Hamilton et al. 2004). It is incidentally caught by gill nets in the Philippines.

Surgeonfishes show varying degrees of habitat preference and utilization of coral reef habitats, with some species spending the majority of their life stages on coral reef while others primarily utilize seagrass beds, mangroves, algal beds, and /or rocky reefs. The majority of surgeonfishes are exclusively found on coral reef habitat, and of these, approximately 80% are experiencing a greater than 30% loss of coral reef area and degradation of coral reef habitat quality across their distributions. However, more research is needed to understand the long-term effects of coral reef habitat loss and degradation on these species' populations. Widespread coral reef loss and declining habitat conditions are particularly worrying for species that recruit into areas with live coral cover, especially as studies have shown that protection of pristine habitats facilitate the persistence of adult populations in species that have spatially separated adult and juvenile habitats (Comeros-Raynal et al. 2012).